Field of the Invention
The present invention relates to a probe, a subject information acquisition apparatus having the prove, and a method for manufacturing the probe.
Description of the Related Art
As ultrasonic diagnostic devices, devices using photoacoustic waves are provided. The photoacoustic waves are, for example, ultrasound waves produced when a pulse laser (electromagnetic wave) emitted from the outside of a body is absorbed in tissue in the body. Since the photoacoustic waves are produced in specific tissue in the body, imaging of the body tissue using the information of the photoacoustic waves can be performed. Sound waves, ultrasonic waves, photoacoustic waves, and other waves are referred to as acoustic waves. In this specification, they may be represented by the ultrasonic waves.
For detection of the ultrasonic waves produced in the body, a probe can be used. In the probe, an ultrasonic transducer is provided to convert the ultrasonic waves into electrical signals. Conventionally, the ultrasonic transducers using the piezoelectric effect have been used. In recent years, capacitive transducers have also been actively studied and developed. The capacitive transducer includes, for example, cells each having two electrodes provided to sandwich a gap referred to as a cavity maintained in a near-vacuum state, and includes at least one element having at least one cell. One of the two electrodes is fixed to a membrane, and the vibrating membrane having such a structure is held in a state the membrane can vibrate. Vibration of the vibrating membrane by ultrasonic waves changes the distance between the two electrodes, and this causes a change in the capacitance. When voltage is applied between the two electrodes, the capacitance is changed, which is taken out as an electric signals. This is a principle of the ultrasonic wave reception operation. Further, the application of the voltage between the two electrodes also produces the electrostatic attraction. By temporally varying the application voltage, the vibrating membrane vibrates. This is a principle of the ultrasonic wave transmission operation. Among the capacitive transducers, transducers manufactured by applied semiconductor microfabrication techniques are referred to as capacitive micromachined ultrasonic transducers (CMUTs). Probes having a plurality of capacitive transducers (that is, the cells and elements) arrayed at high densities are suitable to achieve high image quality needed in the ultrasonic diagnostic devices.
In the above-described technical field, probes having an acoustic lens disposed on an ultrasonic transducer are proposed (for example, see Japanese Patent Application Laid-Open No. 2008-119318). Further, in the probes having an acoustic lens, a probe in which an anisotropic adhesive and an ultrasonic transducer are electrically connected is provided (see WO2008/114582). In the probes, it is preferable that the acoustic lens is fixed to a capacitive transducer (that is, cells or elements) without positional displacement. The acoustic lens, however, often uses a soft member, for example, silicone rubber, and even though the acoustic lens is positioned at a part of the acoustic lens, the acoustic lens may positionally deviate at the other parts.